1. Field of the Invention
The invention relates to high-surface-area systems adaptable to the immobilization thereon of substrates containing nucleophilic groups, and more particularly to systems adaptable to the immobilization of biologically relevant substances and functional units.
2. Description of the Art
A "biologically relevant" material is one capable of interacting primarily with biological systems and is itself preferably of biological origin.
Both in pure research and in biotechnology, the immobilization of biomacromolecules on support or carrier molecules is among the subjects which have been receiving the closest attention.
So far as the immobilization of enzymes in particular is concerned, the immobilization techniques which have been proposed or are being employed may be classed as follows:
(1) Covalent bonding to a solid support or carrier phase; PA1 (2) Covalent bonding to soluble polymers; PA1 (3) Physical adsorption to a solid support or carrier phase; PA1 (4) Crosslinking at solid surfaces; PA1 (5) Crosslinking with difunctional reagents; PA1 (6) Inclusion in a gel phase; and PA1 (7) Encapsulation. PA1 (a) Esters of acrylic and/or methacrylic acid with C.sub.1 to C.sub.20 alcohols, and in particular the methyl, ethyl, propyl, and butyl esters of methacrylic acid, as well as the methyl, ethyl, propyl, butyl, and 2-ethylhexyl esters of acrylic acid; and PA1 (b) copolymerizable monomers of the vinyl ester type, and in particular vinyl acetate, vinyl propionate, vinyl butyrate and vinyl isobutyrate. PA1 (1) The dispersion must be prepared in a pH range in which the rate of reaction of water with the reactive groups is minimal (as a rule, this will be a pH of about 7); PA1 (2) preparation must take place at as low a temperature as possible; PA1 (3) the polymerization time must be as short as possible; and PA1 (4) strong nucleophiles must not be present in the latex particles. PA1 (1) The latex forms a film at the temperature of application PA1 (2) The latex does not form a film at the temperature of application and/or use PA1 (1) Viruses, prokaryotes and eukaryotes and subunits thereof [see (2)] as well as cellular hybrids such as are used in the production of monoclonal antibodies, for example; and PA1 (2) organelles, and in particular of mitochondria and microsomes, membrane parts, nuclei and subunits thereof.
[See R. D. Falb in "Enzyme Engineering", Vol. II, Ed. E. K. Pye and L. B. Wingard, Plenum Press, 1974; U.S. Pat. No. 3,650,900; Melrose, Rev. Pure and Appl. Chem. 21, 83-119 (1971).]
The technique named under (1) above, covalent bonding to a solid support phase, has so far received the widest attention.
However, it is apparent from the pertinent literature that the manifold tasks which it was hoped could be performed through immobilization of biomacromolecules, such as the purification, separation, and binding of enzymes, the immobilization of microorganisms, affinity chromatography, immune reactions, tasks in clinical diagnostics, etc., cannot be carried out by a single technique. Even where solutions tailored to specific problems are available, as, for example, in the immobilization of specific enzymes on specific supports, translation from the laboratory scale to the technical scale often poses obstacles which are difficult to overcome.
For this reason, many attempts have been made to find solutions which better satisfy technical requirements.
Published Japanese patent application 77 143 281 describes the immobilization of enzymes or microbes by a method in which a film is produced on a glass plate from an aqueous polymer dispersion and an enzyme. The product is used in the form of a foil, which optionally may be comminuted.
These prior art solutions are afflicted with serious drawbacks. As a rule, the surface concentration of the immobilized biologically active substances is too low. Also, the reactive surfaces cannot be enlarged at will by comminution of the polymeric supports since small particles tend to be unstable and frequently do not lend themselves to practical use. While it is known (see above) to bind macromolecular compounds to supports by adsorption, the use of such combinations is limited since the compounds can be readily eluted.
Published unexamined German patent application DE-OS 21 12 740 describes a continuous-flow reactor which has a macroporous reaction core having a polymeric surface comprising adsorption-promoting nitrile, acid amide or ureide groups.
After the enzymes have been physically adsorbed on the solid support phase, crosslinking is effected by means of a dialdehyde, for example.
From published unexamined German patent application DE-OS 22 60 184, a method is known for the preparation of macromolecular compounds immobilized on a carrier. In the method, a macromolecular compound A is first reacted with a compound B having at least one functional group capable of coupling with the macromolecular compound A and at least one further functional group capable of polymerizing. Then a molecular-sieve material of a degree of crosslinking which excludes the macromolecular compound A is added in the unswollen state and the polymerizable group of the coupling product AB is polymerized in the molecular-sieve material, optionally together with further monomers.